Speedo brain teaser

[rionapo]

Originally Posted by jage

They're not- they're both probably 231/250ths EXACTLY. Probably, exactly that.

P.S. Is that the ratio of the circumference of the 16" factory tires and the 17" SMB tires?

[rob_gendreau]

I had learned (perhaps incorrectly) that manufacturers of motorcycles (I'm talking to you, Honda) set their speedos to always read high. But the odometers were always spot on. I'll bet the same is true in cars and trucks; it seems rare that I've ever seen a stock vehicle register low on the speedo.

I was able to recalibrate my speed via my tuner when I changed both my gear ratio and tire size; seems the odo got a bit more accurate as well. But I couldn't tell if it changed both or just one and the other was dependent on that data. I since removed the chip program so I can't go out and figure it out.

At present I show I'm going slower on the speedo than in reality (55 indicated is 59 actual) because of the different gear ratio and tires. I just use my Scan Gauge instead of the speedo. And keep that in mind if you think of buying my van in the future and I list the miles....

Rob

[Pntyrmvr]

Hi;

Six Dodge vans (82 thru 96) and they all have read higher mileage and speed than actual. The 96 has the same error factor as yours.

It helps keep you from speeding and of course shortened the warranty exposure for the factory!

Regards,

Gavin